gg {cccd}

Gabriel Graph

Description

A Gabriel graph is one where the vertices are points and there is an edge between two points if the maximal ball between the points contains no other points.

Usage

gg(x, r = 1, method = NULL, usedeldir = TRUE, open = TRUE, 
   k = NA, algorithm = 'cover_tree')

Arguments

x

a matrix of observations.

r

a multiplier on the ball radius.

method

the method used for the distance. See dist

usedeldir

logical. Whether to use the deldir package or not.

open

logical. If TRUE, open balls are used in the definition.

k

If given, get.knn is used from FNN to approximate the Gabriel graph. Only the k nearest neighbors to the points are used to determine whether an edge should be made or not. This will be much faster and use less memory for large data sets, but is an approximation unless k is sufficiently large.

algorithm

See get.knn.

Details

places an edge between two points i,j if the ball centered between the points with radius r d(i,j)/2 contains no other points.

Value

an object of class igraph. In addition it contains the attributes:

layout

the data.

r, p

arguments passed to gg

Author(s)

David J. Marchette

References

K.R. Gabriel and R.R. Sokal, A New Statistical Approach to Geographic Variation Analysis, Systemic Zoology, 18, 259-278, 1969

D.J. Marchette, Random Graphs for Statistical Pattern Recognition, John Wiley & Sons, 2004.

See Also

rng, dist, get.knn

Examples

x <- matrix(runif(100),ncol=2)

g <- gg(x)
## Not run: 
plot(g)

## End(Not run)